Question: The reference schematics for the FX1 / FX2 / FX2LP do not show termination resistors on the D+ and D- lines. Are termination resistors recommended?

Answer:

The matching series impedance resistors for the USB are internal to the FX1 / FX2 / FX2LP parts, therefore, the FX1 / FX2 / FX2LP does not require termination resistors for the D+ and D- lines. These lines should be connected directly to the USB connector pins with as short a trace as possible, while keeping the traces at 90 ohms differential impedance. Please refer to the application note entitled "High-speed USB PCB Layout Recommendations" for more information.